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							Hardware description | 
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									1 | 
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									Raspberry Pi 
									GPIO used | 
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											PIN# | 
											
											GPIO | 
											
											Functions | 
										 
										
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											3 | 
											
											GPIO2 | 
											  I2C-SDA, 
											battery fuel-gauge systems -reading 
											battery voltage and percentage | 
										 
										
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											5 | 
											
											GPIO3 | 
											   I2C-SCL, 
											battery fuel-gauge systems -reading 
											battery voltage and percentage | 
										 
										
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											31 | 
											
											GPIO6 | 
											  AC power loss 
											& power adapter failture detection, 
											Low-power supply failed, High-power 
											supply OK | 
										 
										
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											36 | 
											
											GPIO16 | 
											  Control 
											battery charging, High-charging 
											disabled, Low-charging enabled  | 
										 
									 
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									 *The UPS connects to the 
									Pi GPIO via pogo pins, If the I2C address 
									(0x36) is not detected or failed to read AC 
									power state or failed to control charging, 
									please ensure to clear the leads of the pins 
									used on the GPIO header from the bottom of 
									the Raspberry Pi PCB and then reinstall it. 
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									2 | 
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									Battery voltage 
									level indicators | 
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											Battery voltage range (V) | 
											
											D1 | 
											
											D2 | 
											
											D3 | 
											
											D4 | 
											
											Remark | 
										 
										
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											3.87-4.2 | 
											ON | 
											ON | 
											ON | 
											ON | 
											
											
											discharging levels of 100% | 
										 
										
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											3.7-3.87 | 
											ON | 
											ON | 
											ON | 
											OFF | 
											
											
											discharging levels of 75% | 
										 
										
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											3.55-3.7 | 
											ON | 
											ON | 
											OFF | 
											OFF | 
											
											
											discharging levels of 50% | 
										 
										
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											3.4-3.55 | 
											ON | 
											OFF | 
											OFF | 
											OFF | 
											
											
											discharging levels of 25% | 
										 
										
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											Below 3.4 | 
											OFF | 
											OFF | 
											OFF | 
											OFF | 
											low battery | 
										 
									 
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							Required hardware | 
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